Browsing by Author "Clark, Sherrie G."

Now showing 1 - 4 of 4
  • Thumbnail Image
    Achromobacter xylosoxidans in extended semen causes reproductive failure in artificially inseminated sows and gilts
    Clark, Sherrie G. (2008)
    Achromobacter xylosoxidans, a Pseudomonas-like bacterium, contaminated a boar stud laboratory’s water distillation and delivery system that was used for extension of raw semen for artificial insemination. In sow herds that used the contaminated semen, conception rates decreased and vulvar discharges, culled sows, and nonproductive sow days increased. Thorough diagnostic testing revealed that A xylosoxidans was the etiological agent of endometritis and subsequent reproductive failure in these sows and gilts. This is the first known report of female reproductive failure attributed to A xylosoxidans. Routine cleaning and control measures to reduce bacterial growth in the extender ultimately failed to eliminate A xylosoxidans. Following short-term elimination of A xylosoxidans from the extended semen, reproductive parameters in the sow herds returned to their previous levels.
  • Thumbnail Image
    Assisted Reproductive Techniques
    Clark, Sherrie G. (2012-09-29)
    Breeding methods include natural service, artificial insemination, and embryo transfer, with the focus on AI.
  • Thumbnail Image
    Comparison of reproductive performance of AI- and natural service-sired beef females under commercial management
    Marrella, Mackenzie A.; White, Robin R.; Dias, Nicholas W.; Timlin, Claire; Pancini, Stefania; Currin, John F.; Clark, Sherrie G.; Stewart, Jamie L.; Mercadante, Vitor R. G.; Bradford, Heather L. (Oxford University Press, 2021-07)
    The objective of this study was to assess differences in reproductive performance of natural service and artificial insemination (AI) sired beef females based on pregnancy outcomes, age at first calving, and calving interval. Data were sourced from 8,938 cows sired by AI bulls and 3,320 cows sired by natural service bulls between 2010 and 2017. All cows were in a commercial Angus herd with 17 management units located throughout Virginia and represented spring and fall calving seasons. All calves were born to dams managed with estrus synchronization. Pregnancy was analyzed with generalized linear mixed models and other reproductive measures with linear mixed models in R. Six models were evaluated with the dependent variables of pregnancy status at the first diagnosis, pregnancy status at the second diagnosis, pregnancy type (AI or natural service) at the first diagnosis, pregnancy type at the second diagnosis, calving interval, and age at first calving. Independent variables differed by model but included sire type of the female (AI or natural service), prebreeding measures of age, weight, and body condition score, postpartum interval, sex of the calf nursing the cow, and management group. No differences were observed between AI- and natural service-sired females based on pregnancy status at first and second pregnancy diagnosis (P > 0.05). Sire type was only found to be significant for age at first calving (P < 0.05) with AI-sired females being 26.6 ± 1.6 d older at their first calving, which was expected because AI-sired females were born early in the calving season making them older at breeding. Surprisingly, age and body condition score were not significant predictors of pregnancy (P > 0.05). Body weight at breeding was not significant for pregnancy (P > 0.05) but was significant for age at first calving (P < 0.05). These data suggested that lighter heifers calved earlier which contradicts our original hypothesis. Overall, commercial Angus females sired by AI or natural service bulls had similar reproductive performance. Factors that were commonly associated with reproductive success were not significant in this commercial Angus herd managed with estrus synchronization. Given the size of these data, the importance of body condition, age, and weight should be reassessed in modern genetics and management practices.
  • Thumbnail Image
    Vulvar skin temperature changes significantly during estrus in swine as determined by Digital Infrared Thermography
    Clark, Sherrie G.; Scolari, Saara C.; Knox, Robert V.; Tamassia, Manoel A. (2011)
    Objective: To determine if changes in vulvar skin temperature (VST), measured using infrared thermography (IRT), occur during estrus. Materials and methods: The experimental groups consisted of 25 gilts and 27 multiparous sows. Infrared VST and gluteal skin temperature (GST) were measured twice daily (8:00 am and 4:00 pm) using a thermal-imaging camera (Fluke IR FlexCam; Fluke Corporation, Everett, Washington). Once standing estrus was observed, transrectal real-time B-mode ultrasonography was performed twice daily (8:00 am and 4:00 pm) to monitor follicle development and determine time of ovulation. Mean VST and GST (± SEM) were reported and compared using MANOVA and Tukey-Kramer tests in SAS 9.1 (SAS Inc, Cary, North Carolina). Significant differences were reported at P <.05. Results: Evidence of ovulation was detected at approximately 38 ± 9 and 43 ± 12 hours after the onset of estrus in gilts and sows, respectively. Overall, daily VST and GST were significantly higher (P < .05) in sows than in gilts. During estrus, VST rose as estrus began and fell significantly (1.5°C; P < .05) 36 to 12 hours prior to ovulation in both sows and gilts. There was no significant difference between daily GST measurements (P > .05), but the difference between VST and GST was significant (P < .01) over time. Implications: This study demonstrated that VST of sows and gilts, measured by IRT, changes significantly during estrus. The potential to use digital infrared thermography as an adjunct tool during estrus detection in swine appears to be promising.